Phosphatidylcholine is a chemical contained in eggs, soybeans, mustard, sunflower, and other foods. It is found naturally in the body in all cells. Phosphatidylcholine has a lipotrophic mobilizing action that increases the fluidity or permeability of the adipose membrane, which promotes lipid component outflow. This is related to the saturation of fatty acids (when saturation decreases, permeability increases).
Lecithin acts by increasing the action of enzyme that degrade lipids from cellular membrane. In fat cells, this action increases the fluidity and permeability of the adipose membrane, thus facilitating the release of fat from inside and subsequent resorption.